Buckle chute folders are well known in the field of sheet material handling. Typically, a buckle chute folder comprises four or more fold rollers operating in cooperation with two or more buckle chutes and deflectors to fold one or more sheets. A conventional buckle chute includes a stop bar which is adjustably positioned within the chute for folding the sheets to a particular dimension. In operation, a first pair of rollers feeds a stack of sheets (or single sheet) into the first buckle chute. When the leading edge of the stack hits the stop bar in the chute, the first pair of rollers continue to feed the remaining portion of the stack causing the stack to buckle. The buckled portion of the stack is then engaged by another pair of rollers which make the fold in the stack. Examples of buckle chute folders are described in U.S. Pat. No. 4,898,570 issued on Feb. 6, 1990 to H. Luperti, et al. and assigned to the assignee of the present invention; and U.S. Pat. No. 4,842,574 issued on Jun. 26, 1989 to N. Noble.
A known limitation to using buckle chute folders is that buckle chute folders are suitable for folding a limited number of sheets. The proper spacing of the rollers is essential for obtaining the proper fold of a limited number of sheets. When the gap between the roller pairs are set for the feeding and folding of single sheets, there is an inherent limit in the number of sheets that can be folded depending on the characteristics of the sheet material. Typically, a buckle chute folder configured to fold single sheets, will not work well for folding more than 12 or 14 sheets at a time. For inserting machines including buckle chute folders, a stack containing more than 14 sheets must be removed before being folded by the buckle chute folder. Previously, this has required stopping the inserter so that the stack can be manually removed so as to avoid jamming the folder or obtaining a poor fold. An alternative approach to stopping the machine is to divert the large stack from the normal paper path by adding a diverting apparatus upstream from the buckle chute folder.
There are other reasons for diverting sheets from the normal processing path of an inserter, for example, an incomplete stack has been detected. Typically, the devices used to divert sheets from the normal processing path of the inserter machine require the addition of modules or replacing modules in the typical in-line inserter machine configuration. An example of an added module is disclosed in U.S. Pat. No. 5,096,176, issued on Mar. 17, 1992, and assigned to the assignee of the present invention. This module diverts accumulated stacks to a separate bin prior to the stacks being conveyed to the folder. The addition of such a module adds significantly to the size, cost and complexity of the inserter machine. It is also well known to automatically divert stacks that have count, sequence or scanning errors. Generally, this is done at a reject station in the inserter after the stack has been folded and inserted into an envelope.
In U.S. Pat. No. 4,499,834 issued on Feb. 19, 1985 to Ruetschle, et al., there is disclosed a buckle folder having a first deflector which includes a folder gate that is in one position to effect the fold on the sheets and in a second position to bypass the passage through the buckle folder. The buckle folder is situated downstream from a stitcher device that stitches the stack of sheets before the stack is conveyed to the folder. The deflector/gate arrangement disclosed in Ruetschle is not suitable for use with a buckle chute folder because the nature of a buckle chute folder is that the stack is fed into a combination of chutes and chute deflectors.